I cannot change the root password using another user whilst entering the correct root password

>Okay, I can now do it using this command - but why can't I do it using su root passwd - as this is how I used to do it?

Because the 'sudo' command, with no options, expects the first string to be a command that can be found via the PATH environment variable and 'root' is not a command. 'sudo' has always behaved this way.

For su, try specifying -c and path:

su root -c /usr/bin/passwd

Scroll down to the bottom of the su man page for some examples and related details around the syntax.

Apple usually has root user logins disabled — and does provide a GUI path into the password for root.

A) you are switching from sudo to su and they are not the same thing. su prompts of the password you of the account you are attempting to use, and sudo prompts for the password of the account you are currently logged in as and then expects that the account you are logged in as is an admin account or has rights on the /etc/sudoers file. And as NrHuffman has pointed out their command line syntax is different.

B) Mac OS X is not Linux, and you cannot download a Linux binary and expect it to run on Mac OS X. A script maybe, even then the script my want to use a command that does not exist on Mac OS X or a version of a command with options that is not on Mac OS X.

The error message

Cannot execute binary file

is not telling you the binary file cannot be executed it is telling you that the shell at that point does not want a binary file, it is looking for a shell script file.

If you look at the man page for su you will see it takes a number of options then the username you are subbing. Anything after that is sent to the new shell.

So basically you are running (after the switch to the new user)

bash /usr/bin/passwd

which gives

bash-3.2$ bash /usr/bin/passwd

/usr/bin/passwd: /usr/bin/passwd: cannot execute binary file

bash-3.2$

notice the same error you got with su.

Now if you change /usr/bin/passwd to a file with shell commands it works. So

bash-3.2$ cat foo

echo "hello"

bash-3.2$ ls -l foo

-rwxr-xr-x 1 frank staff 13 Jun 2 09:16 foo

bash-3.2$

foo being a file of a single shell command echo "hello" and is executable. Now runt that

bash-3.2$ bash foo

hello

bash-3.2$

no error.

So again the error is misleading, it isnt't telling you it is a bad binary file it is tell ing you it does not want to execute a binary file.

Su and the shell have always behaved this way. I am not sure why your recollection of this is mistaken.

regards

still finding it wierd how the terminal still doesn't want to execute any binary file like that

I guess I wasn;t as clear as I thought I was.

It isn't a bad binary file, the shell will never execute a binary file on startup, again try running

bash /usr/bin/passed

you get the same error as you got when you tried to do thos with su.

Again su and bash have alwasy been this way, your recollection is off.

regards

Proof!:

sh-3.2# su root passwd

/usr/bin/passwd: /usr/bin/passwd: cannot execute binary file

su says that it takes the first argument as the login name, then the rest of the arguments are passwd to the shell, which would be whatever your login shell was set to. The default shell for Mac OS X is bash. "man bash" says:

Bash is an sh-compatible command language interpreter that executes commands read from the standard input or from a file.

it doesn't say anything about the file being a binary program, rather it says it takes commands from that file, so it is expecting the file to be a script (or standard input), not a binary program.

it is the shell that is giving your this error message, no su, not sudo. It is possible that this worked for you in the past because the shell was different, or it was a different version of the shell, or you were on a different operating system, or a different version of the operating system.

Notice this has nothing to do with su, and it is similar for all the shells I tried.

I also tried this on a Linux, Solaris SPARC, Solaris X86, and an IBM AIX system. Same results.

So it is possible, in the past, with a different version of the operating system, with a different shell or shell version, "su root passwd" did work. On Mac OS X today with the shells available, it does not.